如何將嵌套字段的初始值更改為零而不是 null 值。？

Question

如何將嵌套字段的初始值更改為零而不是 null 值。？

在我的情況下，獎品model 是model的OneToOneField

串行器

class PrizeSerializer(serializers.ModelSerializer):
    class Meta:
        model = Prize
        fields = ['title', 'amount']

class AlbumSerializer(serializers.ModelSerializer):
    prize = PrizeSerializer(read_only=True)

    class Meta:
        model = Album
        fields = ['album_name', 'artist', 'prize']

有些項目有獎品數據，但有些沒有獎品數據。 如果沒有獎品數據將顯示為null ,

>>> serializer.data
{
    "album_name": "The Grey Album",
    "artist": "Danger Mouse",
    "prize": null
}

如何將此null值更改為零。？

預期 output

>>> serializer.data
{
    "album_name": "The Grey Album",
    "artist": "Danger Mouse",
    "prize": "0.0"
}

Answer 1

您可以在AlbumSerializer上使用SerializerMethodField ，如下所示：

class AlbumSerializer(serializers.ModelSerializer):
    prize = serializers.SerializerMethodField()

    def get_prize(self, instance):
        if hasattr(instance, 'prize'):
            return PrizeSerializer(instance.prize).data
         return "0.0"

    class Meta:
        model = Album
        fields = ['album_name', 'artist', 'prize']